Disclosed in patent application Ser. No. 14/059,062 is a type of double A-arm suspension configuration derived from Ford's Twin I-Beam front suspension system. This suspension system cooperates with the drivetrain disclosed in patent application Ser. No. 14/087,552 and the steering system disclosed in patent application Ser. No. 14/246,108. These three cooperative functions are installed on a frame, and thereby represent a chassis for a four wheel drive (4WD) vehicle. The frame possesses a ladder-type structure that lies in a single horizontal plane whereby the powertrain is positioned between the frame sides while the frame mounting points for the suspension control links are positioned below the frame sides.
In general, a vehicle's handling characteristics improve as the center of gravity height is decreased. Given that a significant portion of a vehicle's weight is due to the powertrain which in turn affects the center of gravity, then a vehicle's handling characteristics can be improved by decreasing the resting height of the powertrain. Predictably therefore, the handling of a vehicle constructed with the chassis represented by the cited applications can be improved by decreasing the resting height of the powertrain. Resting height refers to the distance that the powertrain resides above the ground.
Decreasing the resting height of the powertrain can be easily achieved by lowering the vehicle closer to the ground; e.g., by reducing the length or spring rate of the suspension springs, a technique widely adopted by sports cars. However such a technique also acts to decrease the ground clearance of the vehicle, an act contrary to the predominant characteristic of any off-road vehicle such as a 4WD vehicle.
Since the chassis represented by the cited applications is directed towards a 4WD vehicle, then a 4WD vehicle constructed with this chassis would acquire improved handling without compromising off-road capability if the resting height of the powertrain was decreased without sacrificing ground clearance. Accordingly, the present invention addresses this issue by offering a chassis design whose powertrain sits lower in the frame without sacrificing ground clearance than does the powertrain in the chassis represented in the cited applications.